Wiki info about Typhoon Mk Ib/L

The Hawker Typhoon was a single engine, single seat fighter which first entered service with the RAF in 1941. Typhoon fighters of the first production series were equipped with a canopy with massive framing and a Rover-produced car-type side door for cockpit access. The first modification of this was to replace some of the solid metal fairings with transparent panels and cut down the pilot’s head armor plate to help increase visibility. Lack of visibility remained a significant problem and whilst a new canopy was being developed, the bulky radio mast and its fairing were replaced with a whip aerial further aft along the fuselage. A new drop-shaped canopy was designed for the pilot's cockpit, providing a good all-round view. The new canopies were fitted on the production aircraft from September 1943 on.
The fighters were equipped with more powerful 2,200 hp Napier Sabre Mk.IIB and 2,260 hp Napier Sabre Mk.IIC engines, as well as new four-bladed de Havilland propellers. The wing-mounted armament consisted of four 20 mm British Hispano Mk.II belt-fed cannons with 140 rounds per gun. The projecting cannon barrels were equipped with fairings to reduce drag.
By the end of 1943, these improvements had been implemented on the majority of the Typhoons already in service.
By the time these later Mk IBs were in service, the aircraft’s shortcomings as a fighter had been identified, but it coped perfectly in the role of a fighter-bomber and a close air-support aircraft, striking German airfields, communication lines, railways, and ships.
Since Typhoons were flown at low altitudes under strong enemy anti-aircraft fire, the designers paid great attention to protecting the pilot and the aircraft's vital systems. The pilot's head and back were protected with an armored backrest and a 38-mm-thick armored glass windscreen. An armor plate protecting the engine was fitted behind the propeller fairing.
After many early teething problems, critical failures and threats to be withdrawn from service altogether, the Typhoon finally found its niche as a rugged, dependable ground attack aircraft. It achieved notoriety amongst German soldiers during the Normandy campaign when, whilst Spitfires were achieving air superiority, the Typhoons were able to cause mayhem amongst German ground units. The Typhoon's production was discontinued in November 1945, and it was withdrawn from service in early 1947. All in all, 3,205 Hawker Typhoon Mk.IB aircraft were produced.